Solve the following FOUR variable linear program using Excel. (You cannot solve this problem easily with the graphical method). MAXIMIZE 2X1 + 5X2 + 3X3 +7X4; subject to the constraints: X1 + X2 + X3 + X4 <= 10; 2X1 + 3X2 + 1X3 + 6X4 <= 17; X1 >= 0; X2 >= 0, X3>= 0, X4 >= 0. Which of the following statements is true about the optimal solution.

If the objective coefficient for X2 is decreased by 0.2, the optimal solution value decreases by 0.7.

X1 has a positive value in the optimal solution without any objective coeff. changes.

The objective coeff. for X4 can be increased to 9 without changing the optimal corner point.

The objective coefficient for X1 can be increased to 5 without changing the optimal corner point.